Cross-reference to Related Applications:
This application relates to the subject matter of a co-pending application by Scott A. Bottorf, Jeffrey D. Russell, and Conway A. Southard, entitled "Moving Map Display", filed on even data herewith and assigned to the same assignee, the Ser. No. of which is 033,298; and to a co-pending application by Scott A. Bottorf, entitled "Surface Texture Generator for Graphics Displays", filed on even data herewith and assigned to the same assignee, the Ser. No. of which is 033,300; the subject matter of both of these applications is incorporated herein by this reference.
Field of the Invention:
The present invention generally relates to avionics moving map displays, and more particularly, is concerned with moving map displays for use in relatively high-speed aircraft, and even more particularly, relates to scrolling image memories for such displays capable of simultaneous loading and displaying of data.
In recent years, in both commercial and military avionics, there has been an expanding requirement for high performance displays to alleviate the problems associated with increased mission complexity, sophisticated avionics capabilities, high crew workload levels, and multisensor weapons systems. It is often desirable for a moving map display to provide the pilot of an aircraft with a display of the terrain over which he is flying his aircraft. Obviously, the update rate necessary to display the terrain below is a function of the aircraft speed, and with the recent advent of low-flying supersonic bombers. the need to rapidly update the moving map display is quickly becoming an important hurdle for avionics engineers.
One system for providing a pilot with a moving map display has been disclosed in U.S. Pat. No. 4,484,192 to William R. Seitz, which is hereby incorporated herein by this reference. The Seitz patent discloses a moving map display system which utilizes a scan memory for storing image data of the area immediately surrounding the vehicle which is to be displayed. As the aircraft travels across the terrain, the image data is updated in the scan memory by providing blanking signals or gaps in the signal from the scan memory to the display. During these blanking signals or gaps, the scan memory is updated with new image data.
Another possible approach is to use a dual blank image memory where the image data is input into one memory bank while the other bank is being scanned.
While these systems, or variations of them, have been used for updating image data in a moving map displays, they do not serious drawbacks. One major drawback with the Seitz design is the inability to rapidly update the image data to the scan memory because the access thereto is limited in time to brief blanking signals. The blanking signals are constrained in duration and frequency by the need to provide a display without visible interruptions or flickering. One drawback of the dual bank image memory is the requirement for two complete memories with the concomitant additional expense, but most importantly, each update would require the full bank of memory to be loaded, thereby causing an unattractive high data transfer rate to occur, because of the loading of much redundant data.
Consequently, a need exists for improvements in image data update for moving map displays which result in an increase image data update rate, while not doubling the image memory.